The use of a flexible liner in standard international container is well known. These liners are inserted within the generally rectangular container and substantially conform to the shape of the rectangular container. These liners can be manufactured using a wide variety of materials including for example polyethylene or polypropylene, and can be made with blown film or woven fabric, both coated and uncoated, as well as possibly including reinforcement, depending on the application. For example, some liners are more abrasion resistant, others more corrosion resistant, while others provide a moisture barrier, etc. These liners substantially cover the inside of the container which then receives a bulk material, the liner preventing the bulk material from contacting the container walls or floor.
In other cases, it is only necessary to include an end face panel, which is provided as a standalone end face panel to prevent the bulk cargo from being discharged when the rear container doors are opened. Another form of flexible insert consists essentially of a flexible end door portion having upper suspension elements such as flexible straps constructed and arranged for suspension from cooperating suspension elements such as cargo rings or attachment straps, fixed to the upper part of a container, a transverse reinforcement constructed and arranged to receive nails or screws or other attachment devices for securing the bottom of the flexible end door portion to the rear end of the floor wall of the container. These end panels may have reinforcing straps interconnecting the flexible rear door portion to a part of the floor and/or walls of the container so that when the container is filled with cargo and the flexible end door portion of the insert is lifted, the reinforcing straps become taut to counteract a tendency for the flexible end door portion to bulge outward. This is typically used in situations where the materials do not harm the walls of the container, or the walls do not contaminate the material, or both.
Some container liners of the prior art have used metal bars positioned across the end face or back panel, which reside in channel edges of the container door to secure the liner. Some other container liners rely on various strap configurations which are attached to the container and extend across the flexible back panel to hold the back panel in position so that it does not bulge out when the container doors are opened.
Care must be taken to insure that the end face or back panel does not move within the container, because relative movement may tear the flexible liner material and cause the contents to spill. Unless steps are taken to maintain the rear end wall in close relation to the corresponding rear end wall of the container, problems arise. Thus, a flexible container liner of the prior art may, even after being secured within the container, have its end panel, which corresponds to the doors of the shipping container, bulge out outwardly into the doorway opening of the container, as filling of the container with bulk product occurs. The bulging may obstruct the closing of the doors of the container. Also bulk cargos have a tendency to move during shipment and this could cause the back panel to bulge outwardly after loading, which could result in a forcible opening of the back doors, which can cause worker injury. This potential for outward bulging can be a problem with containers when opened for inspection before reaching their final destination, as the bulging out can prevent the doors of the container from being reclosed.
While there have been a number of attempts made to address the problem, particularly as to the bulging of the end panel, many of these attempts have suffered from various problems or are difficult or inconvenient to implement. For example, in U.S. Pat. No. 6,662,962, a plurality of straps must be provided and arranged and then free ends of several straps engaged by removable manual tensioning ratchet devices which require significant manual labor to set up and to tension the straps, delaying the loading process, and this manual tensioning can lead to variable strap tension and possibly still result in bulging of the end panel.
A problem with the prior art strap configurations is that they are often difficult and complicated to install. Additionally, restraining the end panel from bulging with multiple straps takes substantial installation time, and often provides variable tension because it requires manually tightening of the straps, which may or may not be sufficient to prevent bulging. Unfortunately, this can only be discovered after the container is filled, when it is too late to take any corrective action.